Apparatus for the interior coating of a cellulose tube

ABSTRACT

This invention relates to an apparatus for the continuous interior coating of a tubular material which comprises a pair of squeeze rolls through which the tube is passed in a substantially horizontal direction, a guide roll for deflecting the tube into a substantially vertical direction, heating means through which the tube passes in the substantially vertical direction, and a second pair of squeeze rolls through which the tube passes after leaving the heating means.

United States Patent Gerigk et al.

[451 Sept. 26, 1972 [54] APPARATUS FOR THE INTERIOR COATING OF A CELLULOSE TUBE Inventors: Gunter Gerigk, Oberursel/Taunus; Wolfgang Klendauer, Wiesbaden, both of Germany Assignee: Kalle Aktiengesellschal't, Wiesbaden- Biebrich, Germany Filed: 7 Nov. 5, 1970 Appl. No.: 87,129

Related US. Application Data Division of Ser. No. 783,892, Dec. 16, 1968, Pat. No. 3,556,701.

[30] Foreign Application Priority Data Dec. 18, 1967 Germany ..P 16 21 990.2

US. Cl ..ll8/407, 1 l8/DlG. 10 Int. Cl ..B05b 13/6, B05c 7/04, B05c 8/04 Field of Search ..l 17/51, 97; ll8/DIG. l0, DIG.

[56] References Cited UNITED STATES PATENTS l,956,722 5/1934 Kennedy ..l l8/DIG. l0 2,lO0,587 11/1934 Chalker ..l l8/DlG. 10 2,210,436 8/1940 Weingand et al. ..1 l8/DlG. l0 2,602,959 7/1952 Fenlin ..l l8/DIG. ll 2,824,020 2/1958 Cook et al. ..l l7/5l 3,567,495 3/1971 Gajos ..l l8/408 Primary Examiner-Henry S. Jaudon Attorney-James E. Bryan [57] ABSTRACT This invention relates to an apparatus for the continuous interior coating of a tubular material which comprises a pair of squeeze rolls through which the tube is passed in a substantially horizontal direction, a guide roll for deflecting the tube into a substantially vertical direction, heating means through which the tube passes in the substantially vertical direction, and a second pair of squeeze rolls through which the tube passes after leaving the heating means.

2 Claims, 1 Drawing Figure PATENTEDsme I972 INVENTORS GUNTER GERIGK WOLFGANG KLENDAUER Z M-v ATTORNE APPARATUS FOR THE INTERIOR COATING OF A CELLULOSE TUBE This application is a division of copending application Ser. No. 783,892, filed Dec. 16, 1968, now U.S. Pat. No. 3,556,701.

The present invention relates to an apparatus for the interior coating of a cellulose tube.

It is known to provide tubes of regenerated cellulose or of a fibrous fleece or a fabric filled or coated with regenerated cellulose with a layer of a natural or, more advantageously, a synthetic resin. which also may contain a plasticizer, in order to reduce the permeability thereof to water vapor. Further, it is known to be of advantage for some purposes, e.g., when the cellulose tubes are to be used as artificial sausage casings, for the plastic layer to be on the inside of the tube.

The continuous production of tubes having an internal plastic coating is simple when the tubes are made from a cellulose web provided on one or both surfaces with a plastic layer, taking care that a coated side of the cellulose web is turned into the interior of the shaped tube, and the tube is then formed by making a sewn, bonded or welded longitudinal seam along the tube. The continuous production of tubes having an interior lining of plastic material is more complicated when the plastic lining is to be applied to the inner surface of a tube material. Interior coating of a finished tube is necessary when the tube to be coated is seamless, i.e., has been produced without the intermediate formation of a web of material bounded by two rims, or when the longitudinal seam of a tube formed from a web of material must be covered by the plastic material during internal coating.

Processes and apparatus for continuously coating the inside of tubes with plastic materials are known. In

these processes, a solution of the plastic material is poured into a section of the tube, the tube is then advanced in the longitudinal direction past the plastic solution poured into it, so that its interior wall is wetted while sliding past the plastic solution enclosed in the interior thereof, and the tube thus wetted on the inside is then dried until a solid interior layer of plastic has formed.

For performing an interior coating process, an apparatus is known, e.g., in which a section of the tube is squeezed between two pairs of squeeze rolls and wetting of the tube is effected in this section by means of a liquid enclosed therein.

When lacquers, i.e., plastic material dissolved in organic solvents, are used, the known interior coating processes yield practically no suitable interior coatings. Aqueous dispersions of plastic materials, the use of which has considerable advantages as compared with the use of plastic materials in organic solvents, could not be successfully employed for the known processes, since continuous plastic layers of even thickness could not be satisfactorily produced on the inside wall of the tube material by this process.

According to a process which has become known recently, a tubular cellulose material is produced which consists of a regenerated cellulose layer on the outside and a layer of a polyvinylidene chloride copolymer on the inside, the copolymer layer being applied from an aqueous dispersion or from a solution of the plastic material in an organic solvent. ln this process, the outer surface of a tubular material whose walls consist essentially of regenerated cellulose, is coated with the aq ueous dispersion of the plastic or with the lacquer, and after the production and drying of the outside layer, the tubular material is turned inside out so that the coating is now on the interior surface of the tube. By this process, layers of a constant thickness may be produced, but it can not be performed continuously. Further, turning the tubular material inside out is rather troublesome.

The present invention provides an apparatus by means of which a tubular material containing regenerated cellulose is provided with an interior layer in a reliable manner, which is comparatively easy to operate continuously, by applying an aqueous dispersion of a plastic thereto.

The process, which may be performed with the apparatus of the invention, is based upon the process for the continuous interior coating of a preferably fiberreinforced tubular material comprising regenerated cellulose, in which this material is conducted in the longitudinal direction past a coating liquid containing a thermoplastic material which is enclosed in a section thereof, so that the inside wall thereof is wetted with the coating liquid, the wetted tubular material is then filled with a gas, preferably air, and dried until an interior layer of the plastic material has formed. The tubular material is caused to pass the coating liquid, comprising an aqueous dispersion of a plastic material, in a vertical direction. The tubular material wetted in this manner is first dried and then heated until the plastic particles originating from the dispersion have melted and formed an interior layer of plastic material. The tubular material, after having passed the plastic dispersion, is kept in a gas-filled state until the interior layer of plastic has formed, and being conducted vertically upwardly until the plastic dispersion wetting the interior thereof has lost so much of its water content that it is no longer capable of flowing at the drying temperature prevailing. The plastic material contained in the plastic dispersion preferably is either a copolymer containing at least per cent by weight of vinylidene chloride, or a copolymer containing at least 80 per cent by weight of vinyl chloride. The process of the invention can be operated continuously with particular case, when the tubular material is caused to pass the plastic dispersion enclosed therein first in a horizontal direction and then vertically upwardly.

In the process performed with the apparatus of the present invention, a tubular material may be used which comprises a seamless regenerated cellulose tube. When the tubular material to be provided with an interior layer by the process of the invention is to be reinforced with fibers, it may be produced, e.g., from a web of long-fibered paper which is formed into a tube, closed longitudinally by means of a seam of viscose thread, then provided in known manner on its inside with a viscose layer, which latter is transformed into a regenerated cellulose layer, whereupon the tubular material thus obtained is dried. The preparation of such fibrereinforced tubular materials has been described, e.g., in U.S. Pat. Nos. 2,045,349 and 2,105,273. The tubular material may be used in the dried state or also in the wet state, when the regenerated cellulose is still in the gel state.

In order to achieve a better adhesion of the plastic layer to the inside of the tube, the tube material employed may be coated on its inner surface with a known anchoring agent, e.g., a water-soluble melamine formaldehyde resin or a urea-formaldehyde resin. However, dispersions of plastic materials also are known which by themselves have an anchoring effect.

The apparatus according the the present invention may be used for an interior coating process which can be continuously performed in a particularly easy manner. It includes means by which the tubular material is advanced in its longitudinal direction through a first pair of squeeze rolls formed by two horizontal rolls arranged one above the other and through a second pair of squeeze rolls, and through a drying means between these two pairs of squeeze rolls, the apparatus also including a guide roller mounted adjacent the first pair of squeeze rolls and, above the guide roller, the drying means with a vertical passage therein is arranged in such a manner that between the first pair of squeeze rolls and. the guide roller the tubular material has a horizontal direction of travel, and between the guide roller and the drying means the tubular material has a vertical direction of travel. Because of a more advantageous utilization of space, the apparatus is particularlyadvantageous when it also includes a second drying means with a vertical passage therein adjacent the first drying means, and a second guide roller mounted above both drying means, the second guide roller causing the tubular material to move in a vertical direction through the first drying means between itself and the first guide roller, and to move in a vertical direction through the second drying means between itself and the second pair of squeeze rolls positioned beneath the second drying means.

In the apparatus of the invention, the tube passes through the initial pair of squeeze rolls in any direction desired, preferably however in'a horizontal direction. If it passes the first pair of squeeze rolls in. a direction other than vertically upwardly, it is deflected vertically upwardly after passing the first pair of squeeze rolls. After leaving the first pair of squeeze rolls, the tube is filled with the aqueous dispersion of a plastic material at least until it has taken the vertically upward direction. Thereafter, but in any case before it enters the drying means, the tube is filled with air or another suitable gas and remains gas-filled until it has passed the second pair of squeeze rolls, which, according to the present invention, must not occur before a plastic layer has formed from the plastic dispersion lining the inner wall of the tube. v

The second pair of squeeze rolls may be mounted above the drying means but, alternatively, the gas-filled tube may pass the second pair of squeeze rolls after it has been deflected by a guide roller from its vertically upward direction. However, according to the invention, deflection must not occur before the plastic dispersion lining the inner wall of the tube has lost so much of the water content thereof that it is incapable of flowing at the prevailing drying temperature.

This loss of water is partially due to the drying process, and partially due to the fact that the regenerated cellulose tube is capable of absorbing water from the dispersion. The dispersion may be considered not flowable when its migration velocity on the inner wall under the influence of gravity does not exceed 1 mm. per minute.

The plastic substance contained in the aqueous dispersion may comprise copolymers produced from at least per cent by weight of vinylidene chloride. As the second polymerization component, the copolymers preferably contain vinyl chloride, acrylonitrile, acrylic acid esters or acrylic acid. Alternatively, the dispersed plastic may be a vinyl chloride copolymer containing at least 80 per cent by weight of vinylchloride with the remainder being vinyl acetate or maleic acid esters. Aqueous dispersions of other plastics also may be used, provided they comply with the requirement that they considerably reduce the permeability to water vapor.

The first and second pairs of squeeze rolls are driven. They impart different speeds to the tube, because the tube tends to shrink during the process of the invention. The difference in the speeds of the two pairs of squeeze rolls determines the degree to which the tube is allowed to shrink and, thus, the degree of longitudinal tension created in the tube between the two pairs of squeeze rolls.

By the apparatus of the invention, a very uniform interior coating may be continuously applied to the tube. Further, the process can be performed very easily, in particular it is not difficult to adjust the process conditions in the desired manner. In a perferred embodiment of the process, it is relatively easy to employ the coating dispersion in the form of a coherent quantity of liquid, which is free from gas bubbles at the beginning of the process, in the desired section of the tube.

In order to refill a quantity of plastic dispersion without interruption of the operation into the tube when this becomes necessary due to the consumption during coating, the tubular material is severed before entering the first pair of squeeze rolls, the dispersion is filled into one of the two open ends produced by severing the tube, and the two open ends are then connected by means of a piece of rubber hose, taking care, by appropriately squeezing the tube either manually or with mechanical means, while the first pair of squeeze rolls is opened for a short time, that the refilled plastic dispersion and the piece of rubber hose are on the other side of the first pair of squeeze rolls, when the pair is closed again. Replenishing also is relatively simple when the process of the invention is applied in its preferred embodiment, in which the section of the tube filled with the plastic dispersion is first conducted in a horizontal and then in a vertically upward direction. Advantageously, replenishing of the plastic dispersion is adapted to the lengths of tube produced in the spinning process, so that the quantity to be refilled can be introduced into the naturally occuring open ends of the tubular material. While it is unavoidable in most cases that after replenishing of the dispersion, air bubbles are in that section of the tube which should be free of them and should, instead, be filled with the dispersion, this condition persists for only a very short time because it is a characteristic feature of the present process that the process conditions in this respect readjust themselves at once.

The apparatus according to the invention will be further illustrated in detail by reference to the accompanying drawing. This drawing is a diagrammatic representation of an apparatus for performing the preferred embodiment of the invention.

In the apparatus shown, the tubular material S to be coated on the interior thereof is withdrawn from a delivery roll 1 and, after being coated, rewound on wind-up roll 2. For this purpose, the tubular material passes through a first pair of squeeze rolls 3, 4 consisting of the rolls 3 and 4 mounted one above the other, moves in a horizontal direction for some distance, which may, e.g., be 50 cm to l m, and is then deflected by the guide roller 5 to move vertically upwardly. On its way upward, the tubular material passes through a drying channel 6, which may have a length of 8 m, for ex ample, and may consist of a double-walled tube between the walls of which steam may be introduced under high pressure. Before entering the drying channel, the tubular material S, which may consist of a dried tube or a tube in the gel state, entrains a uniform film of liquid on the interior thereof from the aqueous plastic dispersion D enclosed within the tubular material in a section beginning after the first pair of squeeze rolls 3, 4 and extending into the vertically upward portionof the tubular material between the guide roller 5 and the entrance to the drying channel 6. The quantity of dispersion enclosed may be, e.g., 4 liters. The portion of the tubular material not filled with the enclosed dispersion is filled with air, until the tubular material passes a second pair of squeeze rolls 7 and 8 consisting of the rolls 7 and 8 positioned side by side.

In the drying channel, the aqueous dispersion lining the inner wall of the tubular material loses so much water that it is no longer capable of flowing.

After leaving the drying channel 6, and before reaching the second pair of squeeze rolls 7 and 8, the tubular material is deflected by a second guide roller 9 and conducted downwardly, through a second drying channel 10 which is similarly double walled and heated by high pressure steam.

In order to conduct the leading edge of the tubular material through the two drying channels at the beginning of operation, a threading device is provided consisting of 4 pulleys ll, 12, 13, and 14 with an endless cord 15 running over the pulleys, to which cord the leading edge of the tubular material may be fastened. The cord 15 runs over the pulleys 11 to 14, through the drying channel 6, around the guide roller 9, through the drying channel 10, and back to the drying channel 6.

At the lower ends thereof, the drying channels 6 and 10 are provided with sealing members of cloth which tightly surround the tubular material and thus prevent the ingress of cold air.

Beneath the second drying channel, a conditioning chamber 16 is provided in which the coated tubular material is exposed to a humid atmosphere, so that it may absorb the desired quantity of water.

The invention will be further illustrated by reference to the following specific examples:

Long-fibered manila paper having a weight of 25 g/m an absorptive capacity of 40 mm (capillary rise of distilled water in a 15 mm. wide strip), and a wet strength of 2.14 kg in the longitudinal direction and of 2.33 kg in the transverse direction (measured on a 15 mm. wide strip of which 100 mm. were clamped in a Schopper apparatus), is continuously formed into a tube by closing the longitudinal seam with a viscose thread. The inside of the paper tube thus obtained is coat dwithaviscose contai in 7 rce tb w i ht f cellulose and 5.7 percent by veiht 0 f cabstic so a solution and having a salt index of 2 The viscose, which has penetrated into the paper is precipitated in an aqueous bath containing 8 per cent by weight of sul furic acid, 15 per cent by weight of ammonium sulfate, and 10 per cent by weight of sodium sulfate, and regenerated into cellulose; the tubular material is then de-sulfurized in known manner and passed through a plasticizer bath. After the tubular material has left the plasticizer bath, the regenerated cellulose on its inside which is still in the form of a gel is coated with an aqueous solution of a resin-like, water-soluble melamine/formaldehyde condensate and then wound upon a delivery spool in the form of a flat tube. The wound-up tube may be in the form of a gel tube or of a dried tube.

In an apparatus as shown in the drawing, the inside of the tube is coated with a lining of a copolymer of about parts by weight of vinylidene chloride and l0 parts by weight of methyl acrylate.

For this purpose, a sufficient quantity, for example 4 liters, of an aqueous dispersion of the copolymer containing l to 15 per cent by weight of copolymer on a dry basis, is filled into the open end of the tubular material, included in a section of the tube of an appropriate length by pinching the tube off either by hand or by means of a clamp, and the tube is then introduced into the opened first pair of squeeze rolls. The further procedure is as described above. If a gel tube is used, the passage of the tube through the drying channels is slower than in the case of a dried tube, because a higher drying capacity is required due to the higher water content.

A tubular material is thus obtained the inside of which is covered with a continuous layer of the copolymer in a quantity of about 5 to 15 g per m and a thickness of about 6 to 12p..

It will be obvious to those skilled in the art that many modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.

What is claimed is:

1. Apparatus for the continuous interior coating of a tubular material which comprises a pair of squeeze rolls through which the tube is passed in a substantially horizontal direction, a guide roll for deflecting the tube into a substantially vertical direction, heating means through which the tube passes in the substantially vertical direction, and a second pair of squeeze rolls through which the tube passes after leaving the heating means.

2. Apparatus according to claim 1 including a second guide roll for deflecting the tube through about after leaving the heating means, and a second heating means positioned between the second guide roll and the second pair of squeeze rolls.

FORM PO-105O (IO-69) UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION 3,693,588 September 26, 1972 Patent No. Dated Inventor(s) Gunter Gerigk et 6.1.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the cover sheet, in the heading, itemEQ "Division of Ser. No. 783,892, Dec. 16, 1968, Pat. No. 3,556,701"

should read Division of Ser. No. 783,892, Dec. 16, 1968,

Pat. No. 3,628,592

Column 1, lines L and 5, delete ",now 11.3. Pat." No. 3,5S6,70l"

and substitute now 'U.S. Pat. No. 3', 628,592

Signed and sealed this lL th day of May 197R.

(SEAL) Attest:

c. MARSHALL DANN EDWARD l-'I .FLE'IGIIER J I Commissioner of Patents Attesting Officer 

1. Apparatus for the continuous interior coating of a tubular material which comprises a pair of squeeze rolls through which the tube is passed in a substantially horizontal direction, a guide roll for deflecting the tube into a substantially vertical direction, heating means through which the tube passes in the substantially vertical direction, and a second pair of squeeze rolls through which the tube passes after leaving the heating means.
 2. Apparatus according to claim 1 including a second guide roll for deflecting the tube through about 180* after leaving the heating means, and a second heating means positioned between the second guide roll and the second pair of squeeze rolls. 